1. Field of the Invention
The present invention relates, generally, to clutch assemblies for use in automotive transmissions. More specifically, the present invention relates to a two piece clutch assembly having a twist lock joint.
2. Description of the Related Art
Generally speaking, land vehicles require three basic components. These components include a power plant (such as an internal combustion engine), a power train and wheels. The power train's main component is typically referred to as the "transmission". Engine torque and speed are converted in the transmission in accordance with the tractive-power demand of the vehicle. Automotive vehicle transmissions include One or more gear sets which may include an inner sun gear, intermediate planet gears which are supported by their carriers and outer ring gears. Various components of the gear sets are held or powered to change the gear ratios in the transmission. The disc pack clutch is a device which is commonly employed as a holding mechanism in a transmission. The disc pack clutch assembly has a clutch subassembly including a set of plates and a set of friction discs which are interleaved between one another. The plates and friction discs are bathed in a continual flow of lubricant and in one disposition normally turn past one another without contact. The clutch assembly also typically includes a piston subassembly. When a component of a gear set is to be held, as for example during a gear change, a piston supported in the piston subassembly is actuated so as to cause the plates and friction discs to come into frictional contact with respect to one another.
In the past, clutch and piston subassemblies were joined together to form the disc pack clutch assembly either during the assembly of the transmission itself or immediately prior to this step. However, over the past few years, there has been a continual demand made on the suppliers of such components to provide "systems" rather than parts so that the assembly process at the vehicle manufacturing plant may be further simplified. To meet this need, the clutch and piston subassemblies can be held together prior to installation in the transmission using a plurality of spring retainer clips. Three retainer clips can be employed to clamp the two subassemblies together. Alternatively, pins and/or rivets may be employed for the same purpose. One disadvantage of this arrangement is that it adds steps in the manufacturing process and creates waste in the used retainer clips. In addition, pins and rivets do not allow for relative adjustments between the piston and clutch housings. Typically, the heads on the rivets must be ground off. Furthermore, assemblies using pins and/or rivets suffer from the disadvantage that they are rather permanent fasteners and once employed, the assembly lacks serviceability. Thus, there remains a need in the related art to reduce the number of parts that are employed during the manufacture of automotive components, such as clutch assemblies for transmissions allow for relative adjustments between assembled parts, when necessary and allow the assembly to be easily serviced.
Not only do the clutch and piston subassemblies need to be packaged together, but the clutch assembly must be specifically positioned relative to the transmission casing so as to align an apply pressure port in the piston housing with a corresponding port in the transmission casing through which fluid pressure is supplied to the piston to engage the plates and friction discs. Thus, it is important that the clutch assembly be accurately positioned relative to the transmission housing so that the proper fluid ports are aligned. Clutch assemblies in the related art suffer from the disadvantage in that there is no convenient way to quickly and accurately locate the clutch assembly relative to the transmission casing. Therefore, there is a further need to simplify the overall process of mounting clutch assemblies in automotive transmissions.